<?php

namespace App\Services\PressRelease;

use App\Enums\Portal;
use App\Models\PressRelease;
use Illuminate\Support\Str;
use Symfony\Component\HttpFoundation\Response;

/**
 * Erzeugt den Veröffentlichungsnachweis-PDF laut Decision-Update §2.3
 * („PM XY wurde am … auf … veröffentlicht" inkl. URL, Datum, Vorschau).
 * On-demand aus vorhandenen PM-Daten — keine KI, kein externer Renderer
 * (gleicher schlanker PDF-Ansatz wie der Legacy-Rechnungs-Renderer).
 */
class ProofPdfRenderer
{
    private const PAGE_WIDTH = 595;

    private const PAGE_HEIGHT = 842;

    private const LEFT = 70;

    private const RIGHT = 525;

    public function downloadResponse(PressRelease $pressRelease): Response
    {
        $pdf = $this->render($pressRelease);

        return response()->streamDownload(
            static function () use ($pdf): void {
                echo $pdf;
            },
            $this->filename($pressRelease),
            [
                'Content-Type' => 'application/pdf',
                'Cache-Control' => 'private, max-age=0, must-revalidate',
            ],
        );
    }

    public function filename(PressRelease $pressRelease): string
    {
        return 'Veroeffentlichungsnachweis-PM-'.$pressRelease->id.'.pdf';
    }

    public function render(PressRelease $pressRelease): string
    {
        $content = '';
        $portalLabel = $pressRelease->portal instanceof Portal
            ? $pressRelease->portal->label()
            : (string) $pressRelease->portal;
        $publishedAt = $pressRelease->published_at;
        $dateLabel = $publishedAt?->format('d.m.Y') ?? 'n/a';
        $timeLabel = $publishedAt?->format('H:i') ?? null;

        $content .= $this->text(self::LEFT, 790, 'Veröffentlichungsnachweis', 22, 'F2');
        $content .= $this->line(self::LEFT, 778, self::RIGHT, 778, 0.7);
        $content .= $this->text(self::LEFT, 760, $portalLabel, 11, 'F2');

        $y = 712.0;
        $headline = $timeLabel
            ? "Diese Pressemitteilung wurde am {$dateLabel} um {$timeLabel} Uhr auf {$portalLabel} veröffentlicht."
            : "Diese Pressemitteilung wurde am {$dateLabel} auf {$portalLabel} veröffentlicht.";
        $y = $this->wrappedText($content, self::LEFT, $y, $headline, 11, self::RIGHT - self::LEFT, 16);

        $y -= 24;
        $content .= $this->text(self::LEFT, $y, 'Titel', 9, 'F2');
        $y = $this->wrappedText($content, self::LEFT, $y - 15, (string) $pressRelease->title, 13, self::RIGHT - self::LEFT, 17, 'F2');

        $y -= 18;
        foreach ($this->metaRows($pressRelease, $portalLabel, $dateLabel) as [$label, $value]) {
            $content .= $this->text(self::LEFT, $y, $label, 9, 'F2');
            $this->wrappedText($content, self::LEFT + 110, $y, $value, 9, self::RIGHT - self::LEFT - 110, 12);
            $y -= 20;
        }

        $y -= 10;
        $content .= $this->text(self::LEFT, $y, 'Vorschau', 9, 'F2');
        $this->wrappedText($content, self::LEFT, $y - 15, $this->previewText($pressRelease), 9, self::RIGHT - self::LEFT, 12);

        $content .= $this->line(self::LEFT, 70, self::RIGHT, 70, 0.5);
        $content .= $this->text(self::LEFT, 56, 'Erstellt über pressekonto – maschinell erzeugter Nachweis.', 8);

        return $this->buildPdf($content);
    }

    /**
     * @return list<array{0: string, 1: string}>
     */
    private function metaRows(PressRelease $pressRelease, string $portalLabel, string $dateLabel): array
    {
        return array_values(array_filter([
            ['Portal', $portalLabel],
            ['Veröffentlicht', $dateLabel],
            ['URL', $this->publicUrl($pressRelease)],
            $pressRelease->category?->name ? ['Kategorie', (string) $pressRelease->category->name] : null,
        ]));
    }

    private function publicUrl(PressRelease $pressRelease): string
    {
        $base = match ($pressRelease->portal) {
            Portal::Presseecho => config('domains.domain_presseecho_url'),
            Portal::Businessportal24 => config('domains.domain_businessportal_url'),
            default => config('app.url'),
        };

        return rtrim((string) $base, '/').'/'.ltrim((string) $pressRelease->slug, '/');
    }

    private function previewText(PressRelease $pressRelease): string
    {
        $plain = trim(html_entity_decode(strip_tags((string) $pressRelease->text)));

        return Str::limit($plain, 600);
    }

    private function buildPdf(string $content): string
    {
        $objects = [
            "1 0 obj\n<< /Type /Catalog /Pages 2 0 R >>\nendobj\n",
            "2 0 obj\n<< /Type /Pages /Kids [3 0 R] /Count 1 >>\nendobj\n",
            "3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 ".self::PAGE_WIDTH.' '.self::PAGE_HEIGHT."] /Resources << /Font << /F1 4 0 R /F2 5 0 R >> >> /Contents 6 0 R >>\nendobj\n",
            "4 0 obj\n<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding /WinAnsiEncoding >>\nendobj\n",
            "5 0 obj\n<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica-Bold /Encoding /WinAnsiEncoding >>\nendobj\n",
            "6 0 obj\n<< /Length ".strlen($content)." >>\nstream\n{$content}endstream\nendobj\n",
        ];

        $pdf = "%PDF-1.4\n";
        $offsets = [0];

        foreach ($objects as $object) {
            $offsets[] = strlen($pdf);
            $pdf .= $object;
        }

        $xrefOffset = strlen($pdf);
        $pdf .= "xref\n0 ".(count($objects) + 1)."\n";
        $pdf .= "0000000000 65535 f \n";

        foreach (array_slice($offsets, 1) as $offset) {
            $pdf .= sprintf("%010d 00000 n \n", $offset);
        }

        $pdf .= "trailer\n<< /Size ".(count($objects) + 1)." /Root 1 0 R >>\n";
        $pdf .= "startxref\n{$xrefOffset}\n%%EOF\n";

        return $pdf;
    }

    private function escapePdfText(string $text): string
    {
        $encoded = iconv('UTF-8', 'Windows-1252//TRANSLIT//IGNORE', $text);

        return str_replace(['\\', '(', ')'], ['\\\\', '\(', '\)'], $encoded ?: Str::ascii($text));
    }

    private function text(float $x, float $y, string $text, int $size = 9, string $font = 'F1'): string
    {
        return sprintf(
            "BT /%s %d Tf %.2F %.2F Td (%s) Tj ET\n",
            $font,
            $size,
            $x,
            $y,
            $this->escapePdfText($text),
        );
    }

    private function line(float $x1, float $y1, float $x2, float $y2, float $width = 0.5): string
    {
        return sprintf("%.2F w %.2F %.2F m %.2F %.2F l S\n", $width, $x1, $y1, $x2, $y2);
    }

    private function wrappedText(
        string &$content,
        float $x,
        float $y,
        string $text,
        int $size,
        float $width,
        float $lineHeight = 12,
        string $font = 'F1',
    ): float {
        foreach ($this->wrap($text, $width, $size) as $line) {
            if ($line !== '') {
                $content .= $this->text($x, $y, $line, $size, $font);
            }

            $y -= $lineHeight;
        }

        return $y;
    }

    /**
     * @return list<string>
     */
    private function wrap(string $text, float $width, int $size): array
    {
        $lines = [];
        $maxCharacters = max(8, (int) floor($width / ($size * 0.5)));

        foreach (explode("\n", str_replace(["\r\n", "\r"], "\n", $text)) as $paragraph) {
            if (trim($paragraph) === '') {
                $lines[] = '';

                continue;
            }

            $line = '';
            foreach (preg_split('/\s+/', $paragraph) ?: [] as $word) {
                $candidate = trim($line.' '.$word);
                if ($line !== '' && Str::length($candidate) > $maxCharacters) {
                    $lines[] = $line;
                    $line = $word;

                    continue;
                }

                $line = $candidate;
            }

            if ($line !== '') {
                $lines[] = $line;
            }
        }

        return $lines;
    }
}